This work develops a method for onboard estimation of wind field with spatial and temporal variation based on local wind vector estimation and/or measurements from multiple aircraft flying in the same airspace. Aircraft flying in the same airspace of operation are considered airborne wind sensors scattered over the airspace because of the fact that aircraft carry along with them wind information inherent in their dynamics and kinematics. The onboard wind field estimation is formulated in the framework of parameter estimation based on various wind field models, which are different function of position and time. The online wind field estimation is utilized in trajectory prediction of aircraft flying in spatially and/or temporally varying wind. Various simulation cases are presented to demonstrate the feasibility of wind field estimation and the benefit of using such information in trajectory prediction.
This research effort develops a guidance and control system for a small airship to fly through assigned waypoints in three dimensional space with a desired speed in the presence of wind and wind gust. In the control system development and validation, a simulation environment based on the nonlinear 6-DOF model of an airship, including the effect of the wind, is used. The controller design is based on MIMO (Multi-Input Multi-Output) LQR (Linear Quadratic Regulator) method. A gain scheduling scheme is used to cover multiple operating conditions based on the forward speed. Nonlinear simulations for different scenarios are performed and results are discussed. The simulation experiments show that the airship can fly through the assigned waypoints, even when the way points are at different altitudes,
After a structural damage or component failure during any §ight mode, aircraft dynamics are dramatically altered. A quick and adequate stabilization e¨ort is crucial. Flight dynamics for several failure scenarios are analyzed. Necessary amounts of control de §ections for postfailure trim are calculated. These trim values are used as control input in an open loop manner and validity of this approach is tested via §ight simulations. Alternatively, a closed loop §ight control system, which does not need the postfailure trim values, is also designed. This closed loop controller is based on a linearized aircraft model whereas §ight simulations are based on nonlinear aircraft dynamics.
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